This application is based on and claims priority from Japanese Application No. P03-261483 filed Jul. 4, 1991, the disclosure of which is incorporated by reference herein.
The present invention relates to a mechanically simplified two-group lens system of the telephoto type. Particularly, it relates to a zoom lens system that is used with a compact camera and that has a shorter back focus than that of the zoom lens system of a single-lens reflex camera.
Conventional two-group zoom lens systems, which have been used with compact cameras, have a zoom ratio of about 2. These conventional zoom lens systems have an overall lens length (i.e. the distance between the lens surface closest to the object and the image plane) at the narrow-angle or telephoto end that is longer than the focal length at the telephoto end.
However, if a zoom lens system, having an overall length that is greater than its focal length, is assembled in a camera, the overall equipment size cannot be made satisfactorily compact. Moveover, when the zoom lens system's overall size is reduced, each of the lens groups must be provided with more power. However, if the power of each lens group is increased, greater variations in aberrations will occur during a zooming operation.